1. Field of the Invention
The present invention generally relates to image forming apparatuses such as a copy machine, a facsimile machine or a printer and, more particularly, to a conveyance unit used in an image forming apparatus having a paper eject part above an image forming part, an image forming apparatus having such a conveyance unit and a front-side plate frame structure having a reinforcing member that constitutes a front side of an image forming apparatus.
2. Description of the Related Art
In an image forming apparatus, such as a copy machine, a facsimile machine or a printer, an image forming part forms a visible image on a recording medium such as a recording paper in accordance with image data that is acquired by reading a document reading part, received from an external apparatus through a communication line such as a telephone network or sent from a host computer. After the visible image are formed on the recording paper, the recording paper is conveyed to a paper eject part so as to eject the recording paper to outside. More specifically, the image forming part of the image forming apparatus forms a latent image on an image carrier such as a photoconductor in accordance with the image data, develops the latent image by developer in a developing device so as to visualize the image data, transfer the visible image onto a transfer material such as the recording paper by a transfer device, and fixes the transferred visible image by a fixing device. Then, the image forming part conveys the recording paper, which has been subjected to the fixing process, to the paper eject part that ejects the recording paper onto a paper eject tray, etc.
In an image forming apparatus such as a copy machine, a facsimile machine or a multi-function machine having a printer function, it is general to locate a document reading part above an image forming part that forms an image and arrange a paper supply part under the image forming part. For this reason, a paper-eject part such as a paper-eject tray onto which copies or printed papers are provided on a side of the image forming apparatus. However, when the paper-eject part is provided on a side of the apparatus, an occupied area of the apparatus is increased, which causes a problem in that a location for installing the image forming apparatus is restricted especially in a narrow office.
In order to achieve a compact structure by omitting a part protruding on a side of the image forming apparatus, a paper eject space may be provided inside the body of the image forming apparatus so as to place an internal paper-eject part in the paper eject space. Such an image forming apparatus is suggested in patent documents 1)-3) mentioned below. Specifically, the paper-eject space is provided between an image forming part and a document reading part, and the internal paper-eject part is constituted by providing a paper-eject tray in the paper-eject space. Moreover, in the image forming apparatus having such an internal paper-eject part, in order to convey printed papers, on which images are formed by the image forming part, to the internal paper-eject part, an upward conveyance part is provided in an area from the image forming part to a side of the internal paper eject part so as to convey and eject the printed papers to the internal paper-eject part.
In the image forming apparatus having such an internal paper-eject part, although an occupied area of the apparatus can be maintained small since the paper-eject space is provided between the image forming part and the document reading part, there is a problem in that a height of the image forming apparatus is increased. Particularly, if a multi-stage paper-eject part is located under the image forming apparatus, a height of the image forming apparatus is considerably increased. For this reason, in order to maintain the height of the image forming apparatus within an allowable range, a space for providing the image forming part must be reduced. However, if the space for mounting the image forming part is reduced, the workability of maintenance of the image forming apparatus is sacrificed. Moreover, when a paper jam, etc., occurs in the conveyance path of papers, there is a problem that it is difficult to perform an operation to remove the named papers.
Moreover, the image forming apparatus provided with the internal paper-eject part has a structure in which a front side of the internal paper-eject part of the apparatus body is open so that printed papers ejected on the tray of the internal paper-eject part can be easily taken out. For this reason, there is a problem that strength of the front side of the apparatus body is reduced. Thus, a structure of maintaining the strength of the front side is adopted in which a plate-like frame is provided on the front side of the image forming part to support the front side of the paper-eject tray. However, in this case, the workability of a maintenance work and an operation for paper jamming is deteriorated.
1) Patent Document: Japanese Laid-Open Patent Application No. 8-339108
2) Patent Document: Japanese Laid-Open Patent Application No. 2002-296857
3) Patent Document: Japanese Laid-Open Patent Application No. 2002-46922